The city’s potty-parity rule for offices is getting flushed down the toilet at Nomura’s new headquarters at Worldwide Plaza.

The building owner, a group led by George Comfort & Sons, is seeking permission to install far fewer toilets for women on the Japanese financial giant’s lower levels — presumably the male-dominated trading floors.

The owners of the 59-story West Side tower want the “water closets and lavatories” on these floors to be divvied up 75/25 because for “certain financial-services operations” the population is historically comprised of 75 percent men and 25 percent women, according to a document filed with the city.

All bathroom humor aside, the city’s plumbing code requires that the number of toilets for women be equal to the number of toilets and urinals in men’s restrooms.

The owners are getting around the rule by using historical data to show that potty parity doesn’t make sense.

To get the go-ahead for a new Certificate of Occupancy, the buildings department required the owners to file a “Plumbing Fixture Distribution Restrictive Declaration.” Signed by a Comfort exec in October, it was filed with the city earlier this month.

The document promises that if any of the fourth through seventh floors is no longer leased by Nomura, equal restroom treatment would be restored or the Certificate of Occupancy could be yanked.

The buildings department did not return an e-mail or calls for more information.

Robert Brubaker, program manager for the American Restroom Association, said normally the arguments for restroom inequity involve obvious places such as dorms and prisons.

“This is the first time we’ve heard it from a business,” he said. “They could get into a thing where they say they can’t hire more women because they don’t have enough toilets.

“No American company would dare ask for this.”

Steve Solomon, a spokesperson for George Comfort & Sons, declined to comment, while Nomura officials couldn’t be reached.